The present invention relates to the drilling of sealed fluid containers such as low or high pressure gas mains, storage tanks and the like and the installation of a permanent stopper or plug for preventing the escape of fluid under pressure from a sealed container. A combination hand cylinder drill for drilling fluid containers and a tool for inserting a stopper in a hole through the container wall to prevent the escape of fluid is provided.
The pipe fittings installed in underground systems for the delivery of gas to residential and commercial users can, over time, develop leaks which require the attention of gas utility companies. Fittings such as pipe tees connected to pipe mains that carry gas under pressure which can be as low as one quarter pound or as much as fifty pounds per square inch or more can become so worn or damaged as to permit leakage of substantial volumes of gas to the atmosphere, creating an environmental hazard and posing a risk of explosive combustion. Such leaks must be promptly sealed, preferably without interruption of service to gas consumers. Similarly, fittings in a wide array of fluid container applications such as, e.g., petrochemical or water transmission lines, storage tanks or the like may develop leaks or become less than fully functional. Such fittings need to be replaced without interrupting service or draining storage reservoirs.
One solution to the problem of pipe leakage in the past has been to excavate a trench extending in both the upstream and downstream directions from the leak and cutting off gas flow through the pipe after installing a bypass and welded fittings to remove and replace the section of pipe to which the leaking fitting is connected. Alternatively, there are devices for installation in the pipe both upstream and downstream of a leaking fitting which serve temporarily to interrupt fluid flow while a pipe section that includes a leaking fitting is disconnected at both ends and replaced with or without a new fitting. Both of these prior art approaches are time and labor consuming.
Other methods of replacing leaking pipe fittings are known which allow fluid under pressure to escape to the atmosphere while the leaking valve or other fitting is being replaced. In the case of natural gas or petrochemical pipelines, for instance, such methods require special equipment such as fire resistant clothing and respirators for the workers, and the released gas or other flammable or explosive fluid constitutes a safety hazard.
U.S. Pat. No. 2,763,282 describes a pipe stopper fitting which, when installed, completely closes off the internal passage through a pipe and shuts off gas flow through the pipe.
Devices for sealing an opening in a pipe wall during removal of a pipe fitting are shown in U.S. Pat. Nos. 4,127,141; 4,239,055 and 5,099,868 . The arrangements of all of these patents involve the installation of temporary pressure plugs made of rubber or other compressible material to provide a gas-tight seal for a hole in a pipe wall. The pressure plugs of these three patents are removed from the pipe after use, and are not intended to be left permanently in place. Removal of the pressure plugs when the pipe has been provided with a new fitting or a pipe saddle not only takes time but also leaves some uncertainty about the possibility of leakage after pipe repair has been completed.
Also, my U.S. Pat. No. 5,511,578 , incorporated herein by reference, describes and claims a tool for installing a stopper in a gas conduit wall. The use of the tool of U.S. Pat. No. 5,511,578 for repairing a leak such as a leaking fitting in a pressurized pipe for supplying gas under pressure produces a permanent internal seal at a hole in the pipe section that has been repaired in addition to the external seal provided by a plug held in place on the pipe section by a saddle or the like. The invention of U.S. Pat. No. 5,511,578 provides a method for sealing an opening through the side wall of a linear pipe section, such as a main carrying gas under pressure. Such a seal is required when a defective pipe fitting such as a tee or a valve must be removed. The valve or tee or other fittings has a passage that extends at an angle of 90 degrees to the axis of the pipe to which the fitting is attached. The fitting to be removed is also adapted for installation of a gate valve or the like which also has a cylindrical passage that forms a linear continuation of the passage through the fitting. Thus, when a gate valve is mounted on the pipe fitting which is to be removed, there is a continuous passage through the fitting and the gate valve extending radially at a right angle to the axis of the pipe section. The tool of the invention serves to insert a stopper plug through this passage to the location of the hole in the pipe section side wall that is to be sealed. The tool can be safely used without the need for workers to wear protective clothing or gas masks while the pipe under repair continues to carry a flow of gas under pressure. The tool is of simple, reliable construction and easy to use. However, a separate tool is required to drill a hole, if necessary, before the hole is plugged.
The present invention provides a tool for drilling a hole in a fluid container such as a gas main and for then inserting a stopper through the drilled hole. The present invention provides for an advance over prior art tapping or drilling devices in that only one tool may be used both to drill and plug the hole.
The present invention is a combination device comprised of a hand cylinder drill used for drilling sealed fluid containers such as low or high pressure gas mains, storage tanks and the like and for use in inserting a stopper in the drilled hole through the container wall to prevent the escape of fluid under pressure from the sealed container.
The hole plugging aspect of the present invention is used to insert a stopper plug into a hole in a fluid container wall. The stopper plug includes a compressible, elastomeric, generally cylindrical sealing member. The sealing member expands radially when axially compressed, to close the hole tightly against the escape of gas under pressure from within the pipe. Compressive force is applied to the stopper plug by the cooperation of threads on a rod member which extends axially through the stopper plug with a toggle or anchor that has a pair of wings that extend to engage the inner wall of the pipe upon rotation of the threaded rod. When the expanded plug stopper is securely in place, sealing the hole, the threaded rod-like member is separated from the elongated shaft which had served to rotate the stopper plug, leaving the stopper plug in place, sealing the hole. The defective fitting is removed, for example, by sawing the fitting off. In the case where the hole that is plugged is in a pipe side wall, a pipe saddle, clamp or other fitting, which can receive a rigid plug, is then secured around the pipe at the location of the internally sealed hole to provide a permanent external closure of the hole and to serve as an additional restraint against movement of the stopper plug.
The rotatable shaft that is used to rotate the rod member of the stopper plug extends through a threaded, cylindrical nipple member or housing which can be threadedly secured to a shut off valve that has been attached to the leaking fitting so that leakage does not occur while the stopper plug is being positioned and secured in the hole in the pipe wall. The nipple preferably has a stopcock for bleeding off whatever gas is contained in the nipple. Cessation of fluid flow from the stopcock shows that the hole has been sealed and relieves pressure from the housing to facilitate safe removal of the tool from the fitting or valve.
The rotatable shaft has attachment means, which may be internal threads, for removable attachment to the socket. The rotatable shaft also has attachment means, which may be external threads, for removable attachment to a drill bit or hole saw cutter.
The shaft is provided at its end remote from the stopper plug with a handle for manual rotation of the shaft to open the wings of the toggle and compress the elastomeric member so that it expands radially to seal the hole. The shaft is also provided with means remote from the drill bit for connection to a handle or power device for manual or powered rotation of the shaft and a drill bit.
The first step in the operation of a tool in accordance with the invention is to attach a gate valve or the like to the pipe fitting that is to be removed. Then after drilling or sawing the container wall with the drill aspect of the invention, if necessary, to ensure that the hole to be plugged is circular, the stopper plug is inserted through the gate valve and the fitting. The stopper plug has a toggle that engages the inner wall of the pipe or container wall section. A radially expanding body of the stopper plug is expanded in place to close the hole against the escape of the fluid contents of the pipe or container. The tool is removed, leaving the stopper plug in place and the fitting is cut off just above the location of the stopper plug, leaving a stub of the removed fitting on the pipe. In the case of a pipe, a clamp, saddle, collar or similar known device is installed around the pipe section and around the stub of the fitting that has been removed.
The combination drill and stopper installation tool eliminates the need for repair personnel to carry two different tools for the drilling and installation procedures. The present invention also is an advance over prior art drilling, tapping or plugging devices in that a bypass valve is optionally provided to equilibrate fluid pressure on either side of the drill face so that, in the case of high pressure fluids, insurmountable resistance is not encountered to applying the drill surface to the material to be drilled.